1. Fields of the Invention
The present invention relates to a pneumatic nozzle for roller coating, especially to a pneumatic nozzle for roller coating that coats a coating material smoothly in a non-contact way and controls the thickness of the coating material in micron scale so as to manufacture three-dimensional microstructures on rollers for producing roller dies and increase the practical value.
2. Descriptions of Related Art
The most optimal manufacturing process of flexible electronics industry available now is the roll to roll process while how to coat a uniform film on a roll is a key technique in manufacturing of the molding die. The coating methods available now are as followings: slot die coating, roll to roll coating and doctor blade coating.
1. Refer to US Pat. App. No. 2006/0102036 A1, published on May 18, 2006, a method of coating a printing roll by slits is disclosed. By control of the amount of printing material flowing out of the printing device and the size of the slit, the thickness of the coating material is controlled. However, such way is not an optimal method for manufacturing of roll dies due to high technical requirements and high manufacturing cost.
2. Refer to Taiwanese Pat. App. No. 577360, published on Feb. 21, 2004-uniform coating device, the device includes a pressure member, a blade member and a coating member. The pressure member generates a pushing power source that pushes the blade member so as to control contact pressure between the blade member and the coating member. One end of the blade member is pushed by the pressure member while the other end is contacted with the coating member. By control of a force applied, the thickness of the film attached on surface of the coating member is controlled. The coating member contacted with the blade member can rotate so as to attach a chemical film on the surface thereof and then roll to process the chemical film for coating the film uniformly on the surface. However, in practice, this method is unable to produce films in micron (μm) scale and the uniformity is difficult to achieve.
3. Refer to U.S. Pat. No. 5,755,883, published on May 26, 1998, a roll coating device relating to a roll to roll coating is revealed. The coating device includes two rolls—a coating roll and a coating liquid transfer roll. After a coating liquid supplier supplying a predetermined amount of coating liquid on the coating liquid transfer roll, the coating liquid transfer roll rotates and an outer circumferential face of the coating liquid transfer roll contacts an elastic outer circumferential face of the coating roll so as to coat liquid. However, this method adjusts the thickness of the coating according to the distance between the two rolls. Thus the method has the same disadvantage as the Doctor Blade Coating method—it is unable to achieve production of films in micron scale is unable.
4. Refer to U.S. Pat. No. 5,582,868, published on Dec. 10, 1996, an intermittent coating process and an apparatus for coating of a sheet without wrinkling thereof is disclosed. The apparatus includes a plurality of rolls so as to prevent the occurrence of wrinkles or folds in the base sheet and improve accuracy of coating of the base sheet. Thus this method also can't control the thickness of the sheets precisely in micron scale. Moreover, selection of materials for rolls is quite important because certain kind of material is easily to cause wrinkles on the base sheet.
Thus there is a need to develop a pneumatic nozzle for coating roll that overcomes above shortcomings and has more practical value.